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Full-Text Articles in Mechanical Engineering

Meniscus Modeling And Emission Studies Of An Ionic Liquid Ferrofluid Electrospray Source Emitting From A Magneto-Electric Instability, Brandon Jackson Jan 2018

Meniscus Modeling And Emission Studies Of An Ionic Liquid Ferrofluid Electrospray Source Emitting From A Magneto-Electric Instability, Brandon Jackson

Dissertations, Master's Theses and Master's Reports

This dissertation presents three studies on the electrospray of ionic liquid ferrofluid. Ionic liquid ferrofluids are electrically conductive super-paramagnetic fluids which respond strongly in the presence of electric and magnetic fields. When a small reservoir of ionic liquid ferrofluid is positioned within a magnetic field, magnetic stresses will deform the fluid interface into a peak. The addition of a strong electric field will further stress the fluid interface until a threshold stress is reached at which point the surface tension cannot contain the combined stresses and a spray of fluid or ions results at the apex. This process is termed ...


A New Technique To Determine Accommodation Coefficients Of Cryogenic Propellants, Kishan Bellur Jan 2018

A New Technique To Determine Accommodation Coefficients Of Cryogenic Propellants, Kishan Bellur

Dissertations, Master's Theses and Master's Reports

The control of propellant boil-off is essential in long-term space missions. However, a clear understanding of cryogenic propellant phase change and the values of accommodation coefficients are lacking. To that effect, a new method to determine accommodation coefficients using a combination of neutron imaging, thin film evaporation modeling and CFD modeling has been established. Phase change experiments were conducted in the BT-2 Neutron Imaging Facility at the National Institute of Standards and Technology (NIST) by introducing cryogenic vapor (H2 and CH4) at a set pressure into Al6061 and SS316L test cells placed inside a 70mm cryostat. Condensation is achieved by ...


Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune Jan 2017

Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune

Dissertations, Master's Theses and Master's Reports

Two electrospray sources were developed to operate on an ionic liquid ferrofluid; one source was a pressure‑fed capillary electrospray source and the other was a novel electrospray source which used a magnetically‑induced instability to produce a peak from which an electric field could extract electrospray. Multiple characteristics of electrospray operation were examined for both sources using faraday plates/cups, a quartz crystal microbalance, a retarding potential analyzer, and a time-of-flight mass spectrometer. The ILFF electrosprays for a capillary source were shown to operate in a mixed ion/droplet regime. The mass flow of the electrospray beam was primarily ...


Restraint System Design And Evaluation For Military Specific Applications, Sebastian Karwaczynski Jan 2016

Restraint System Design And Evaluation For Military Specific Applications, Sebastian Karwaczynski

Dissertations, Master's Theses and Master's Reports

This research focuses on designing an optimal restraint system for usage in a military vehicle applications. The designed restraint system must accommodate a wide range of DHM’s and ATD’s with and without PPE such as: helmet, boots, and body armor. The evaluation of the restraint systems were conducted in a simulated vehicle environment, which was utilized to downselect the ideal restraint system for this program.

In December of 2011 the OCP TECD program was formulated to increase occupant protection. To do this, 3D computer models were created to accommodate the entire Soldier population in the Army. These models ...


Transient Thermoelectric Supercooling: Isosceles Current Pulses From A Response Surface Perspective And The Performance Effects Of Pulse Cooling A Heat Generating Mass, Alfred Piggott Jan 2015

Transient Thermoelectric Supercooling: Isosceles Current Pulses From A Response Surface Perspective And The Performance Effects Of Pulse Cooling A Heat Generating Mass, Alfred Piggott

Dissertations, Master's Theses and Master's Reports

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no ...


Rapid Space Trajectory Generation Using A Fourier Series Shape-Based Approach, Ehsan Taheri Jan 2014

Rapid Space Trajectory Generation Using A Fourier Series Shape-Based Approach, Ehsan Taheri

Dissertations, Master's Theses and Master's Reports - Open

With the insatiable curiosity of human beings to explore the universe and our solar system, it is essential to benefit from larger propulsion capabilities to execute efficient transfers and carry more scientific equipment. In the field of space trajectory optimization the fundamental advances in using low-thrust propulsion and exploiting the multi-body dynamics has played pivotal role in designing efficient space mission trajectories. The former provides larger cumulative momentum change in comparison with the conventional chemical propulsion whereas the latter results in almost ballistic trajectories with negligible amount of propellant. However, the problem of space trajectory design translates into an optimal ...